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How To Build An Extension

Step 1: What type of extension do you need?

If you’re thinking about adding an extension to your home, it’s a good idea to start by considering why you want to add an extension and what the function of the new space will be. This will help to determine the type of extension required (single storey/two storey/loft conversion etc) and the design of the final layout of your home.

Sometimes there may be multiple ways to achieve your objective – if you’re not entirely sure how you want to extend your home or would just like some alternative ideas, Yoop Architects can take a measured survey of your property, then draw it all up in 3D and create sketches to show sometimes five or six options to achieve your desired result.

Step 2: Who will design your new layout?

You don’t have to work with an architect to design your extension – you can choose to design it yourself, opt for a build and design company, work with an Architectural Technologist or anyone else that has the knowledge and expertise to design your extension.

However, there are many advantages to hiring an architect over another type of designer. For example, all architects must be registered with the Architects Registration Board (ARB) which means they are obligated to follow the ARB code of conduct and you have more rights if something were to go wrong at any stage.

Additionally, a local architect should have a good understanding of the local authorities guidance and planning policies and also help to make sure that the building conforms to UK Building Regulations.

The disadvantages of hiring an architect are mainly their fees. However, a good architect will be working to help you keep within budget and their expertise allows them to see possibilities that you may not have thought of, potentially helping you to save money overall.

Sometimes there may be multiple ways to achieve your objective - Yoop Architects can take a measured survey of your property and create sketches to show sometimes five or six options to achieve your desired result.

Step 3: Choosing an extension builder

After decades in the construction industry, Yoop Architects have worked with some great builders and can help you find someone who you can trust with your home. We can introduce you to a few, or you might have one or two of your own in mind.

When choosing a builder, it’s important to find someone who’s reputable, reliable and that you get on with on a personal level. They should be able to offer a guarantee/warranty and formal, detailed quotations/contacts. For more tips, check out ‘Tips For Choosing A Builder’ to find the right builder to turn your plans into reality.

FREE GUIDE: Category: Home Extensions
FREE: How To Design A Home Extension

Inside this easy to read free guide, discover how to design your home extension.

Step 4: Planning Permission & Neighbours

As long as your house is quite original and unmodified, a lot of home extension/conversion projects come under permitted development (which means you don’t need to apply for planning permission – it’s granted automatically). This means you can just start building. However, we recommend that you apply for a lawful development certificate to prove that the work is covered by permitted development.

If your project is not covered by permitted development, then you’ll need to apply for planning permission. To apply for planning permission, you need to make an application to your local planning authority or via the Planning Portal online application service. (You don’t need to make the application yourself – Yoop can apply for planning permission on your behalf and chase the planning authority up until we get the OK so you don’t have to worry about it)

It’s a good idea to have a chat with your neighbours at this stage about your extension; both as a courtesy and to see if there are likely to be any potential problems/objections. Also, if your extension involves building or digging foundations within 3m of a shared wall or other foundations, then you may require a Party Wall Agreement. This is an agreement which means that your neighbours have given consent to the work being carried out and will protect you and your neighbour if anything goes wrong. 

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Step 5: Building Regulations

The Building Regulations are minimum standards for design, construction and alterations to virtually every building to ensure the safety and health for people in or about those buildings. They cover aspects such as fire safety, insulation, drainage and access.

All extension work requires building regulations approval, however, you do not need to get approval yourself if you use a builder registered with a competent person scheme.

Step 6: How much will your new extension cost?

For build costs, if you worked out a square meter at £1500, that’s a good base price for basic quality. So, for an average single storey extension of 20 square metres, the build cost would be from £30,000 for basic quality

Interior fit out costs vary greatly depending on the function of the room and the quality of appliances but we’ve created a Home Extension Cost Guide to give you a rough idea of prices.

Professional fees such as getting a measured survey, planning and construction drawings, architect design fees, structural engineer fees, contract/project management and VAT work out at around £12,000 for an extension of 20 square metres at a build cost of £30,000 (these may not all be necessary depending on what you are planning).

Permission fees, agreements and additional reports come to around £2000. All together, for a single storey extension of 20 square metres of basic quality, this will give you a minimum spend of £44,000 including most fees, but excluding interior fit-out costs.


If you have any questions about planning and building an extension, or just questions about creating your dream home in general, go ahead and book a free call below with Yoop.


Thinking of your dream home improvement or how to start your project? 
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Post Author: yoopadmin

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